Use of Drilling Parameters for Enhancing Geotechnical Site Investigations

The standard penetration test (SPT) is a proven tool widely used in providing disturbed soil samples to aid in geotechnical site characterization along with estimating soil properties for the design of New Hampshire Department of Transportation (NHDOT) projects. Testing and sampling is typically done at 5 to 10 foot intervals and thus between these samples, use of engineering judgement identifies changes in stratigraphy and the soils respective properties. These tests are used to develop recommendations and aid in the design of NHDOT projects. Performing the SPT in a continuous fashion can be time consuming and labor intensive. The test is also not well-suited for soils containing large particles such as gravel. A technique known as Monitoring-While-Drilling (MWD) makes use of the mechanical response of the drill rig and cutting tools while advancing a borehole. When combined with SPT testing, a continuous quantitative drilling record is produced and the correlated parameters applied into the analysis. This will result in a thorough and accurate representation of subsurface conditions leading to safer and more economical designs. MWD is recognized as an underutilized site characterization tool by the Federal Highway Administration EDC-5: Advanced Geotechnical Methods in Exploration (A-GaME) initiative. The proposed research will assess the use of MWD on roadway and bridge foundation projects for NHDOT. The drilling parameters recorded will be compared to measurements traditionally collected by SPT and the associated soil samples, along with rock cores for deep foundations. Drilling machine parameters controlled by the operator will be collected such as: thrust on drilling tool, rotation rate, and drilling fluid rate. Parameters that directly correspond to the ground response will be collected such as: advance rate, torque, fluid injection pressure and drilling fluid return rate. Other non-controlled parameters will be evaluated to include tool wear and changes in drilling fluid composition. This effort will support more efficient use of design and construction resources and reduces the chance of delays due to unexpected subsurface conditions. Additionally, the information will make an important contribution to the NHDOT Geotechnical Manual and can support mapping efforts and water quality studies performed by other agencies.

Language

• English

Project

• Status: Active
• Funding: $159,757
• Contract Numbers:

  42372F

• Sponsor Organizations:

  New Hampshire Department of Transportation

  John O. Morton Building
  P.O. Box 483
  Concord, NH  United States  03302-0483
• Managing Organizations:

  New Hampshire Department of Transportation

  John O. Morton Building
  P.O. Box 483
  Concord, NH  United States  03302-0483
• Project Managers:

  Nash, Deirdre

• Performing Organizations:

  University of New Hampshire, Durham

  Department of Civil Engineering
  Durham, NH  United States  03824
• Principal Investigators:

  Benoit, Jean

• Start Date: 20210505
• Expected Completion Date: 20230831
• Actual Completion Date: 0
• Source Data: https://www.nh.gov/dot/org/projectdevelopment/materials/research/projects/42372f.htm

Subject/Index Terms

• TRT Terms: Boreholes; Boring; Geotechnical engineering; Monitoring; Subsoil
• Subject Areas: Bridges and other structures; Geotechnology;

Filing Info

• Accession Number: 01771081
• Record Type: Research project
• Source Agency: New Hampshire Department of Transportation
• Contract Numbers: 42372F
• Files: RIP, STATEDOT
• Created Date: May 3 2021 10:09AM